Jace, Cunning Castaway

You can control one legendary Jace, Cunning Castaway in addition to any number of nonlegendary copies of Jace, Cunning Castaway.

The tokens created by Jace's last ability don't have the legendary supertype. If another object becomes a copy of the token, that copy also won't be legendary.

If a token created by Jace's second ability becomes the target of a spell, its ability triggers and goes on the stack on top of that spell. The ability will resolve first (causing the token to be sacrificed). Unless the spell has another target, it will then be countered when it tries to resolve for having no legal targets.